Rupture of non-occlusive cerebrovascular lesions, such as intracranial saccular aneurysms, arterio-venous malformations, and arterio-venous fistulae, is a major cause of stroke. Rupture of a lesion causes subarachnoid hemorrhage in which blood from a ruptured vessel spreads over the surface of the brain. About 2.5% of the United States population (4 million Americans) have an unruptured lesion. About 100,000 of these people suffer a subarachnoid hemorrhage each year. The disease is devastating, often affecting healthy people in their 40's and 50's, with half of the rupture victims succumbing within a month, and with half the survivors becoming seriously disabled as a result of the initial hemorrhage or of a delayed complication.
Neurovascular arteries are generally quite small, having a diameter ranging from 2.0 to 4.0 mm in the Circle of Willis, 2.5 to 5.5 mm in the cavernous segment of the internal carotid artery, 1.5 to 3.0 mm in the vessels of the distal anterior circulation, and 2.0 to 4.0 mm in the posterior circulation. The incidence of non-occlusive cerebrovascular lesions varies with the location, with 50% occurring in the Circle of Willis, 30% in the internal carotid, 15% in the distal anterior circulation, and 5% in the posterior circulation.
Screening for these lesions and preventing rupture will lead to better clinical outcomes and lower costs. Non-invasive treatments for ruptured and unruptured lesions are preferred over surgical interventions due to lower costs, lower mortality and morbidity, and patient preference.
An increasing number of non-invasive treatments are multi-modal, i.e. they utilize two or more different treatments to cure a single lesion. For example, many aneurysms are treated by implanting a stent across the neck of the aneurysm, then filling the aneurysm sac with detachable metallic coils (such as Guglielmi Detachable Coils (Boston Scientific/Target of Fremont, Calif.)) or with a liquid embolic (such as Onyx (Micro Therapeutics, Inc. of San Clemente, Calif.)). Arterio-venous malformations may be treated using a combination of pushable coils, such as those available from Cook Corporation of Bloomington, Indiana, and glue, such as NBCA available from Cordis Neuro Vascular of Miami Lakes, Fla.
However, prior art delivery systems are suitable for only a single treatment modality. As a result, multi-modal treatments require the physicians to utilize several delivery systems. Each time a new delivery system is required, the physician must remove the old delivery system, insert the new delivery system, and re-access the lesion. These extra steps increase the time and the risk of the procedure. It is also possible that it will be impossible to re-access the lesion, resulting in a treatment failure.
It would therefore be valuable to provide a delivery system that permits multi-modal treatment to be performed using a single delivery device.